Analysis of the effect of cone-beam geometry and test object configuration on the measurement accuracy of a computed tomography scanner used for dimensional measurement

Jagadeesha Kumar, Alex Attridge, Paul Wood, Mark A Williams

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

Industrial x-ray computed tomography (CT) scanners are used for non-contact dimensional measurement of small, fragile components and difficult-to-access internal features of castings and mouldings. However, the accuracy and repeatability of measurements are influenced by factors such as cone-beam system geometry, test object configuration, x-ray power, material and size of test object, detector characteristics and data analysis methods. An attempt is made in this work to understand the measurement errors of a CT scanner over the complete scan volume, taking into account only the errors in system geometry and the object configuration within the scanner. A cone-beam simulation model is developed with the radiographic image projection and reconstruction steps. A known amount of errors in geometrical parameters were introduced in the model to understand the effect of geometry of the cone-beam CT system on measurement accuracy for different positions, orientations and sizes of the test object. Simulation analysis shows that the geometrical parameters have a significant influence on the dimensional measurement at specific configurations of the test object. Finally, the importance of system alignment and estimation of correct parameters for accurate CT measurements is outlined based on the analysis.
Original languageEnglish
Article number035105
Number of pages15
JournalMeasurement Science and Technology
Volume22
Issue number3
Early online date4 Feb 2011
DOIs
Publication statusPublished - Mar 2011

Keywords

  • cone-beam geometry
  • spatial dimentions
  • forming
  • moulding
  • computed tomography

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